Our Moon is pretty cool. As I write this column, a full Moon is approaching that will illuminate our night sky. Later, a new Moon will create scary nights and dark, menacing silhouettes lurking throughout the landscape.
Most astronomers believe that our moon was formed by a collision with a Mars-sized asteroid (or planet) several billion years ago.
And there is more to the Moon than just its illumination and ethereal qualities, it keeps the Earth stable. Without the Moon to help steady the Earth’s tilt, experts estimate that our planet’s tilt could increase to 45°, which means that our planet could be spinning on its side, like Uranus. There go the seasons. Think ice ages.
Animals benefit from the Moon as well. Scientists believe that migratory animals use it to navigate. Nocturnal species, both prey and predator, rely on the reflected light (or absence of it).
We learned in grade school that the Moon’s gravitational pull creates our tides. Tides provide the rhythm that has guided our species for thousands of years. Our Moon figures prominently in our culture, our beliefs, our songs, our art, romance, and our literature.
And we now know that our Earth has many moons.
In 2006, astronomers in Arizona detected a peculiar body orbiting the Earth. After taking a closer look, they realized that the object wasn’t a human-generated satellite or space junk. It was an asteroid that had been yanked into an orbit with the Earth.
Scientists dubbed it a mini moon. It was just a few meters in diameter and orbited our Earth for about a year before being ejected.
More mini moons have been discovered. Most are natural space rocks that are drawn into Earth’s gravity, in tagalong orbits with the Earth. One scientist described them as a temporary pet that you keep for a while and then they wander off. (Bad analogy for an animal lover, to be sure.) So these mini moons come and go.
There are other quasi-moons (sometimes dubbed mini moons) circling our Earth…well, sort of. The first one, 3753 Cruithne, was discovered in 1986. It has a diameter of 3 miles (4.8 km). and orbits the Earth every 770 years. The fact that its orbit extends to the sun is so strange that some astronomers argue that it shouldn’t be considered a moon.
Another mini or quasi-moon, named Kamoʻoalewa, was confirmed in 2021 in Hawaii. The name comes from a Hawaiian word meaning a moving celestial object. It’s less than 50 meters (164 feet) in diameter and orbits the Earth in a corkscrew-like pattern, staying at least 40–100 times the distance of the Moon.
In 2023, another mini moon (or quasi-moon) was spotted. Called 2023 FW13, it is a 65-foot asteroid whose orbit extends halfway between Mars and Venus.
And we have other crazy objects orbiting our Earth. In 2018, two dust clouds were discovered orbiting the Earth at the Moon’s L4 and L5 points. These are known as the Kordylewski clouds and have been nicknamed “Earth’s hidden moons.”
Because of their proximity to Earth, mini moons require close scrutiny to ensure that when and if they exit the Earth’s orbit, they are flung into space rather than fall into our atmosphere.
But recently, some experts have eyed mini moons and other near-Earth asteroids for different reasons. They believe that these objects may contain water and valuable minerals for mining or possibly serve as stepping stones for our exploration into the cosmos.
NASA successfully tested the feasibility of extraction in 2016 when it launched the uncrewed OSIRIS-REx spacecraft to collect a sample from the asteroid Bennu. (Bennu is a potentially dangerous asteroid that has a 1-in-2,700 chance of crashing into Earth in 2182.) The NASA spacecraft returned seven years later with a small sample from the 4.5 billion-year-old asteroid.
Mini moon missions to extract minerals would require less fuel and fewer days than journeys to other cosmic bodies, such as the Moon. And due to their small gravitational force they would require little fuel to return to Earth. That is, if these rocks contain water or valuable minerals.
In space exploration, water can be used to create liquid hydrogen rocket fuel and liquid oxygen. Today, spacecraft must carry all of the water and fuel they will need for a round trip. The massive weight added by the fuel results in the “tyranny of the rocket equation,” which states that as payload mass increases, so must the amount of propellant required to break free from the Earth’s gravitational pull. The key to breaking this equation is to discover a way to refuel in space.
Despite these interesting possibilities, the Moon we see most nights remains our sole source for tides and nocturnal illumination. Which is good, because the Moon has figured so prominently in our culture, that we would have to make a lot of changes, just imagine: Harvest Moons, Fly Me to the Moons, Moons’ Light. Which moon would lovers kiss to? Which moon would we have rituals to celebrate? It just doesn’t work.
When I look at the night sky now, I wonder how many little moons are out there, circling our planet until they break free from Earth’s orbit and seek out their own path.
Angela Rieck, a Caroline County native, received her PhD in Mathematical Psychology from the University of Maryland and worked as a scientist at Bell Labs, and other high-tech companies in New Jersey before retiring as a corporate executive. Angela and her dogs divide their time between St Michaels and Key West Florida. Her daughter lives and works in New York City.